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2689 | jermar | 1 | /* |
2 | * Copyright (c) 2008 Jakub Jermar |
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3 | * All rights reserved. |
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4 | * |
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5 | * Redistribution and use in source and binary forms, with or without |
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6 | * modification, are permitted provided that the following conditions |
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7 | * are met: |
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8 | * |
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9 | * - Redistributions of source code must retain the above copyright |
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10 | * notice, this list of conditions and the following disclaimer. |
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11 | * - Redistributions in binary form must reproduce the above copyright |
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12 | * notice, this list of conditions and the following disclaimer in the |
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13 | * documentation and/or other materials provided with the distribution. |
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14 | * - The name of the author may not be used to endorse or promote products |
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15 | * derived from this software without specific prior written permission. |
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16 | * |
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17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
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18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
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20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
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21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
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26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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27 | */ |
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28 | |||
29 | /** @addtogroup fs |
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30 | * @{ |
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31 | */ |
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32 | |||
33 | /** |
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34 | * @file vfs_ops.c |
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35 | * @brief Operations that VFS offers to its clients. |
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36 | */ |
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37 | |||
38 | #include <ipc/ipc.h> |
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39 | #include <async.h> |
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40 | #include <errno.h> |
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41 | #include <stdio.h> |
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42 | #include <stdlib.h> |
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43 | #include <string.h> |
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44 | #include <bool.h> |
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45 | #include <futex.h> |
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46 | #include <rwlock.h> |
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47 | #include <libadt/list.h> |
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48 | #include <unistd.h> |
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49 | #include <ctype.h> |
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50 | #include <assert.h> |
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51 | #include <atomic.h> |
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52 | #include "vfs.h" |
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53 | |||
54 | /** |
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55 | * This rwlock prevents the race between a triplet-to-VFS-node resolution and a |
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56 | * concurrent VFS operation which modifies the file system namespace. |
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57 | */ |
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58 | RWLOCK_INITIALIZE(namespace_rwlock); |
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59 | |||
60 | atomic_t rootfs_futex = FUTEX_INITIALIZER; |
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61 | vfs_triplet_t rootfs = { |
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62 | .fs_handle = 0, |
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63 | .dev_handle = 0, |
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64 | .index = 0, |
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65 | }; |
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66 | |||
2691 | jermar | 67 | static int lookup_root(int fs_handle, int dev_handle, vfs_lookup_res_t *result) |
2689 | jermar | 68 | { |
69 | vfs_pair_t altroot = { |
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70 | .fs_handle = fs_handle, |
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71 | .dev_handle = dev_handle, |
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72 | }; |
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73 | |||
2700 | jermar | 74 | return vfs_lookup_internal("/", strlen("/"), L_DIRECTORY, result, |
75 | &altroot); |
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2689 | jermar | 76 | } |
77 | |||
78 | void vfs_mount(ipc_callid_t rid, ipc_call_t *request) |
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79 | { |
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80 | int dev_handle; |
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81 | vfs_node_t *mp_node = NULL; |
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82 | |||
83 | /* |
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84 | * We expect the library to do the device-name to device-handle |
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85 | * translation for us, thus the device handle will arrive as ARG1 |
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86 | * in the request. |
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87 | */ |
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88 | dev_handle = IPC_GET_ARG1(*request); |
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89 | |||
90 | /* |
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91 | * For now, don't make use of ARG2 and ARG3, but they can be used to |
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92 | * carry mount options in the future. |
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93 | */ |
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94 | |||
95 | ipc_callid_t callid; |
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96 | size_t size; |
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97 | |||
98 | /* |
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99 | * Now, we expect the client to send us data with the name of the file |
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100 | * system. |
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101 | */ |
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102 | if (!ipc_data_write_receive(&callid, &size)) { |
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103 | ipc_answer_0(callid, EINVAL); |
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104 | ipc_answer_0(rid, EINVAL); |
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105 | return; |
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106 | } |
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107 | |||
108 | /* |
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109 | * Don't receive more than is necessary for storing a full file system |
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110 | * name. |
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111 | */ |
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112 | if (size < 1 || size > FS_NAME_MAXLEN) { |
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113 | ipc_answer_0(callid, EINVAL); |
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114 | ipc_answer_0(rid, EINVAL); |
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115 | return; |
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116 | } |
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117 | |||
118 | /* |
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119 | * Deliver the file system name. |
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120 | */ |
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121 | char fs_name[FS_NAME_MAXLEN + 1]; |
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122 | (void) ipc_data_write_finalize(callid, fs_name, size); |
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123 | fs_name[size] = '\0'; |
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124 | |||
125 | /* |
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126 | * Check if we know a file system with the same name as is in fs_name. |
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127 | * This will also give us its file system handle. |
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128 | */ |
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129 | int fs_handle = fs_name_to_handle(fs_name, true); |
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130 | if (!fs_handle) { |
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131 | ipc_answer_0(rid, ENOENT); |
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132 | return; |
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133 | } |
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134 | |||
135 | /* |
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136 | * Now, we want the client to send us the mount point. |
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137 | */ |
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138 | if (!ipc_data_write_receive(&callid, &size)) { |
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139 | ipc_answer_0(callid, EINVAL); |
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140 | ipc_answer_0(rid, EINVAL); |
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141 | return; |
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142 | } |
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143 | |||
144 | /* |
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145 | * Check whether size is reasonable wrt. the mount point. |
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146 | */ |
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147 | if (size < 1 || size > MAX_PATH_LEN) { |
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148 | ipc_answer_0(callid, EINVAL); |
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149 | ipc_answer_0(rid, EINVAL); |
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150 | return; |
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151 | } |
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152 | /* |
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153 | * Allocate buffer for the mount point data being received. |
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154 | */ |
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155 | uint8_t *buf; |
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156 | buf = malloc(size); |
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157 | if (!buf) { |
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158 | ipc_answer_0(callid, ENOMEM); |
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159 | ipc_answer_0(rid, ENOMEM); |
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160 | return; |
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161 | } |
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162 | |||
163 | /* |
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164 | * Deliver the mount point. |
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165 | */ |
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166 | (void) ipc_data_write_finalize(callid, buf, size); |
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167 | |||
168 | /* |
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169 | * Lookup the root node of the filesystem being mounted. |
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170 | * In this case, we don't need to take the namespace_futex as the root |
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171 | * node cannot be removed. However, we do take a reference to it so |
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172 | * that we can track how many times it has been mounted. |
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173 | */ |
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174 | int rc; |
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2691 | jermar | 175 | vfs_lookup_res_t mr_res; |
176 | rc = lookup_root(fs_handle, dev_handle, &mr_res); |
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2689 | jermar | 177 | if (rc != EOK) { |
178 | free(buf); |
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179 | ipc_answer_0(rid, rc); |
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180 | return; |
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181 | } |
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2691 | jermar | 182 | vfs_node_t *mr_node = vfs_node_get(&mr_res); |
2689 | jermar | 183 | if (!mr_node) { |
184 | free(buf); |
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185 | ipc_answer_0(rid, ENOMEM); |
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186 | return; |
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187 | } |
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188 | |||
189 | /* |
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190 | * Finally, we need to resolve the path to the mountpoint. |
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191 | */ |
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2691 | jermar | 192 | vfs_lookup_res_t mp_res; |
2689 | jermar | 193 | futex_down(&rootfs_futex); |
194 | if (rootfs.fs_handle) { |
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195 | /* |
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196 | * We already have the root FS. |
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197 | */ |
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198 | rwlock_write_lock(&namespace_rwlock); |
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2700 | jermar | 199 | rc = vfs_lookup_internal(buf, size, L_DIRECTORY, &mp_res, |
200 | NULL); |
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2689 | jermar | 201 | if (rc != EOK) { |
202 | /* |
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203 | * The lookup failed for some reason. |
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204 | */ |
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205 | rwlock_write_unlock(&namespace_rwlock); |
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206 | futex_up(&rootfs_futex); |
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207 | vfs_node_put(mr_node); /* failed -> drop reference */ |
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208 | free(buf); |
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209 | ipc_answer_0(rid, rc); |
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210 | return; |
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211 | } |
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2691 | jermar | 212 | mp_node = vfs_node_get(&mp_res); |
2689 | jermar | 213 | if (!mp_node) { |
214 | rwlock_write_unlock(&namespace_rwlock); |
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215 | futex_up(&rootfs_futex); |
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216 | vfs_node_put(mr_node); /* failed -> drop reference */ |
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217 | free(buf); |
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218 | ipc_answer_0(rid, ENOMEM); |
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219 | return; |
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220 | } |
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221 | /* |
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222 | * Now we hold a reference to mp_node. |
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223 | * It will be dropped upon the corresponding VFS_UNMOUNT. |
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224 | * This prevents the mount point from being deleted. |
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225 | */ |
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226 | rwlock_write_unlock(&namespace_rwlock); |
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227 | } else { |
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228 | /* |
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229 | * We still don't have the root file system mounted. |
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230 | */ |
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231 | if ((size == 1) && (buf[0] == '/')) { |
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232 | /* |
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233 | * For this simple, but important case, we are done. |
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234 | */ |
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2691 | jermar | 235 | rootfs = mr_res.triplet; |
2689 | jermar | 236 | futex_up(&rootfs_futex); |
237 | free(buf); |
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238 | ipc_answer_0(rid, EOK); |
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239 | return; |
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240 | } else { |
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241 | /* |
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242 | * We can't resolve this without the root filesystem |
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243 | * being mounted first. |
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244 | */ |
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245 | futex_up(&rootfs_futex); |
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246 | free(buf); |
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247 | vfs_node_put(mr_node); /* failed -> drop reference */ |
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248 | ipc_answer_0(rid, ENOENT); |
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249 | return; |
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250 | } |
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251 | } |
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252 | futex_up(&rootfs_futex); |
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253 | |||
254 | free(buf); /* The buffer is not needed anymore. */ |
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255 | |||
256 | /* |
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257 | * At this point, we have all necessary pieces: file system and device |
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258 | * handles, and we know the mount point VFS node and also the root node |
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259 | * of the file system being mounted. |
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260 | */ |
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261 | |||
2691 | jermar | 262 | int phone = vfs_grab_phone(mp_res.triplet.fs_handle); |
2689 | jermar | 263 | /* Later we can use ARG3 to pass mode/flags. */ |
2691 | jermar | 264 | aid_t req1 = async_send_3(phone, VFS_MOUNT, |
265 | (ipcarg_t) mp_res.triplet.dev_handle, |
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266 | (ipcarg_t) mp_res.triplet.index, 0, NULL); |
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2689 | jermar | 267 | /* The second call uses the same method. */ |
268 | aid_t req2 = async_send_3(phone, VFS_MOUNT, |
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2691 | jermar | 269 | (ipcarg_t) mr_res.triplet.fs_handle, |
270 | (ipcarg_t) mr_res.triplet.dev_handle, |
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271 | (ipcarg_t) mr_res.triplet.index, NULL); |
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2689 | jermar | 272 | vfs_release_phone(phone); |
273 | |||
274 | ipcarg_t rc1; |
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275 | ipcarg_t rc2; |
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276 | async_wait_for(req1, &rc1); |
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277 | async_wait_for(req2, &rc2); |
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278 | |||
279 | if ((rc1 != EOK) || (rc2 != EOK)) { |
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280 | /* Mount failed, drop references to mr_node and mp_node. */ |
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281 | vfs_node_put(mr_node); |
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282 | if (mp_node) |
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283 | vfs_node_put(mp_node); |
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284 | } |
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285 | |||
286 | if (rc2 == EOK) |
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287 | ipc_answer_0(rid, rc1); |
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288 | else if (rc1 == EOK) |
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289 | ipc_answer_0(rid, rc2); |
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290 | else |
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291 | ipc_answer_0(rid, rc1); |
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292 | } |
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293 | |||
294 | void vfs_open(ipc_callid_t rid, ipc_call_t *request) |
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295 | { |
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296 | if (!vfs_files_init()) { |
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297 | ipc_answer_0(rid, ENOMEM); |
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298 | return; |
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299 | } |
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300 | |||
301 | /* |
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2700 | jermar | 302 | * The POSIX interface is open(path, oflag, mode). |
303 | * We can receive oflags and mode along with the VFS_OPEN call; the path |
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2689 | jermar | 304 | * will need to arrive in another call. |
2700 | jermar | 305 | * |
306 | * We also receive one private, non-POSIX set of flags called lflag |
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307 | * used to pass information to vfs_lookup_internal(). |
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2689 | jermar | 308 | */ |
2700 | jermar | 309 | int lflag = IPC_GET_ARG1(*request); |
310 | int oflag = IPC_GET_ARG2(*request); |
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311 | int mode = IPC_GET_ARG3(*request); |
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2689 | jermar | 312 | size_t len; |
313 | |||
314 | ipc_callid_t callid; |
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315 | |||
316 | if (!ipc_data_write_receive(&callid, &len)) { |
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317 | ipc_answer_0(callid, EINVAL); |
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318 | ipc_answer_0(rid, EINVAL); |
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319 | return; |
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320 | } |
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321 | |||
322 | /* |
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323 | * Now we are on the verge of accepting the path. |
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324 | * |
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325 | * There is one optimization we could do in the future: copy the path |
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326 | * directly into the PLB using some kind of a callback. |
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327 | */ |
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328 | char *path = malloc(len); |
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329 | |||
330 | if (!path) { |
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331 | ipc_answer_0(callid, ENOMEM); |
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332 | ipc_answer_0(rid, ENOMEM); |
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333 | return; |
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334 | } |
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335 | |||
336 | int rc; |
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337 | if ((rc = ipc_data_write_finalize(callid, path, len))) { |
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338 | ipc_answer_0(rid, rc); |
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339 | free(path); |
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340 | return; |
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341 | } |
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342 | |||
343 | /* |
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344 | * Avoid the race condition in which the file can be deleted before we |
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345 | * find/create-and-lock the VFS node corresponding to the looked-up |
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346 | * triplet. |
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347 | */ |
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348 | rwlock_read_lock(&namespace_rwlock); |
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349 | |||
350 | /* |
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351 | * The path is now populated and we can call vfs_lookup_internal(). |
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352 | */ |
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2691 | jermar | 353 | vfs_lookup_res_t lr; |
2700 | jermar | 354 | rc = vfs_lookup_internal(path, len, lflag, &lr, NULL); |
2689 | jermar | 355 | if (rc) { |
356 | rwlock_read_unlock(&namespace_rwlock); |
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357 | ipc_answer_0(rid, rc); |
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358 | free(path); |
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359 | return; |
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360 | } |
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361 | |||
362 | /* |
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363 | * Path is no longer needed. |
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364 | */ |
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365 | free(path); |
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366 | |||
2691 | jermar | 367 | vfs_node_t *node = vfs_node_get(&lr); |
2689 | jermar | 368 | rwlock_read_unlock(&namespace_rwlock); |
369 | |||
370 | /* |
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371 | * Get ourselves a file descriptor and the corresponding vfs_file_t |
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372 | * structure. |
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373 | */ |
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374 | int fd = vfs_fd_alloc(); |
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375 | if (fd < 0) { |
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376 | vfs_node_put(node); |
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377 | ipc_answer_0(rid, fd); |
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378 | return; |
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379 | } |
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380 | vfs_file_t *file = vfs_file_get(fd); |
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381 | file->node = node; |
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382 | |||
383 | /* |
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384 | * The following increase in reference count is for the fact that the |
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385 | * file is being opened and that a file structure is pointing to it. |
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386 | * It is necessary so that the file will not disappear when |
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387 | * vfs_node_put() is called. The reference will be dropped by the |
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388 | * respective VFS_CLOSE. |
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389 | */ |
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390 | vfs_node_addref(node); |
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391 | vfs_node_put(node); |
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392 | |||
393 | /* |
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394 | * Success! Return the new file descriptor to the client. |
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395 | */ |
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396 | ipc_answer_1(rid, EOK, fd); |
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397 | } |
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398 | |||
399 | static void vfs_rdwr(ipc_callid_t rid, ipc_call_t *request, bool read) |
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400 | { |
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401 | |||
402 | /* |
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403 | * The following code strongly depends on the fact that the files data |
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404 | * structure can be only accessed by a single fibril and all file |
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405 | * operations are serialized (i.e. the reads and writes cannot |
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406 | * interleave and a file cannot be closed while it is being read). |
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407 | * |
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408 | * Additional synchronization needs to be added once the table of |
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409 | * open files supports parallel access! |
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410 | */ |
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411 | |||
412 | int fd = IPC_GET_ARG1(*request); |
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413 | |||
414 | /* |
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415 | * Lookup the file structure corresponding to the file descriptor. |
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416 | */ |
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417 | vfs_file_t *file = vfs_file_get(fd); |
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418 | if (!file) { |
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419 | ipc_answer_0(rid, ENOENT); |
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420 | return; |
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421 | } |
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422 | |||
423 | /* |
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424 | * Now we need to receive a call with client's |
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425 | * IPC_M_DATA_READ/IPC_M_DATA_WRITE request. |
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426 | */ |
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427 | ipc_callid_t callid; |
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428 | int res; |
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429 | if (read) |
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430 | res = ipc_data_read_receive(&callid, NULL); |
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431 | else |
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432 | res = ipc_data_write_receive(&callid, NULL); |
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433 | if (!res) { |
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434 | ipc_answer_0(callid, EINVAL); |
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435 | ipc_answer_0(rid, EINVAL); |
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436 | return; |
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437 | } |
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438 | |||
439 | /* |
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440 | * Lock the open file structure so that no other thread can manipulate |
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441 | * the same open file at a time. |
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442 | */ |
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443 | futex_down(&file->lock); |
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444 | |||
445 | /* |
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446 | * Lock the file's node so that no other client can read/write to it at |
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447 | * the same time. |
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448 | */ |
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449 | if (read) |
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450 | rwlock_read_lock(&file->node->contents_rwlock); |
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451 | else |
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452 | rwlock_write_lock(&file->node->contents_rwlock); |
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453 | |||
454 | int fs_phone = vfs_grab_phone(file->node->fs_handle); |
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455 | |||
456 | /* |
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457 | * Make a VFS_READ/VFS_WRITE request at the destination FS server. |
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458 | */ |
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459 | aid_t msg; |
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460 | ipc_call_t answer; |
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461 | msg = async_send_3(fs_phone, IPC_GET_METHOD(*request), |
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462 | file->node->dev_handle, file->node->index, file->pos, &answer); |
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463 | |||
464 | /* |
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465 | * Forward the IPC_M_DATA_READ/IPC_M_DATA_WRITE request to the |
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466 | * destination FS server. The call will be routed as if sent by |
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467 | * ourselves. Note that call arguments are immutable in this case so we |
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468 | * don't have to bother. |
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469 | */ |
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470 | ipc_forward_fast(callid, fs_phone, 0, 0, 0, IPC_FF_ROUTE_FROM_ME); |
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471 | |||
472 | vfs_release_phone(fs_phone); |
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473 | |||
474 | /* |
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475 | * Wait for reply from the FS server. |
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476 | */ |
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477 | ipcarg_t rc; |
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478 | async_wait_for(msg, &rc); |
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479 | size_t bytes = IPC_GET_ARG1(answer); |
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480 | |||
481 | /* |
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482 | * Unlock the VFS node. |
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483 | */ |
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484 | if (read) |
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485 | rwlock_read_unlock(&file->node->contents_rwlock); |
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486 | else { |
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487 | /* Update the cached version of node's size. */ |
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488 | file->node->size = IPC_GET_ARG2(answer); |
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489 | rwlock_write_unlock(&file->node->contents_rwlock); |
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490 | } |
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491 | |||
492 | /* |
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493 | * Update the position pointer and unlock the open file. |
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494 | */ |
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495 | file->pos += bytes; |
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496 | futex_up(&file->lock); |
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497 | |||
498 | /* |
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499 | * FS server's reply is the final result of the whole operation we |
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500 | * return to the client. |
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501 | */ |
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502 | ipc_answer_1(rid, rc, bytes); |
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503 | } |
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504 | |||
505 | void vfs_read(ipc_callid_t rid, ipc_call_t *request) |
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506 | { |
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507 | vfs_rdwr(rid, request, true); |
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508 | } |
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509 | |||
510 | void vfs_write(ipc_callid_t rid, ipc_call_t *request) |
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511 | { |
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512 | vfs_rdwr(rid, request, false); |
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513 | } |
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514 | |||
515 | void vfs_seek(ipc_callid_t rid, ipc_call_t *request) |
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516 | { |
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517 | int fd = (int) IPC_GET_ARG1(*request); |
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518 | off_t off = (off_t) IPC_GET_ARG2(*request); |
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519 | int whence = (int) IPC_GET_ARG3(*request); |
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520 | |||
521 | |||
522 | /* |
||
523 | * Lookup the file structure corresponding to the file descriptor. |
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524 | */ |
||
525 | vfs_file_t *file = vfs_file_get(fd); |
||
526 | if (!file) { |
||
527 | ipc_answer_0(rid, ENOENT); |
||
528 | return; |
||
529 | } |
||
530 | |||
531 | off_t newpos; |
||
532 | futex_down(&file->lock); |
||
533 | if (whence == SEEK_SET) { |
||
534 | file->pos = off; |
||
535 | futex_up(&file->lock); |
||
536 | ipc_answer_1(rid, EOK, off); |
||
537 | return; |
||
538 | } |
||
539 | if (whence == SEEK_CUR) { |
||
540 | if (file->pos + off < file->pos) { |
||
541 | futex_up(&file->lock); |
||
542 | ipc_answer_0(rid, EOVERFLOW); |
||
543 | return; |
||
544 | } |
||
545 | file->pos += off; |
||
546 | newpos = file->pos; |
||
547 | futex_up(&file->lock); |
||
548 | ipc_answer_1(rid, EOK, newpos); |
||
549 | return; |
||
550 | } |
||
551 | if (whence == SEEK_END) { |
||
552 | rwlock_read_lock(&file->node->contents_rwlock); |
||
553 | size_t size = file->node->size; |
||
554 | rwlock_read_unlock(&file->node->contents_rwlock); |
||
555 | if (size + off < size) { |
||
556 | futex_up(&file->lock); |
||
557 | ipc_answer_0(rid, EOVERFLOW); |
||
558 | return; |
||
559 | } |
||
560 | newpos = size + off; |
||
561 | futex_up(&file->lock); |
||
562 | ipc_answer_1(rid, EOK, newpos); |
||
563 | return; |
||
564 | } |
||
565 | futex_up(&file->lock); |
||
566 | ipc_answer_0(rid, EINVAL); |
||
567 | } |
||
568 | |||
2693 | jermar | 569 | void vfs_truncate(ipc_callid_t rid, ipc_call_t *request) |
570 | { |
||
571 | int fd = IPC_GET_ARG1(*request); |
||
572 | size_t size = IPC_GET_ARG2(*request); |
||
573 | ipcarg_t rc; |
||
574 | |||
575 | vfs_file_t *file = vfs_file_get(fd); |
||
576 | if (!file) { |
||
577 | ipc_answer_0(rid, ENOENT); |
||
578 | return; |
||
579 | } |
||
580 | futex_down(&file->lock); |
||
581 | |||
582 | rwlock_write_lock(&file->node->contents_rwlock); |
||
583 | int fs_phone = vfs_grab_phone(file->node->fs_handle); |
||
584 | rc = async_req_3_0(fs_phone, VFS_TRUNCATE, (ipcarg_t)file->node->dev_handle, |
||
585 | (ipcarg_t)file->node->index, (ipcarg_t)size); |
||
586 | vfs_release_phone(fs_phone); |
||
587 | if (rc == EOK) |
||
588 | file->node->size = size; |
||
589 | rwlock_write_unlock(&file->node->contents_rwlock); |
||
590 | |||
591 | futex_up(&file->lock); |
||
2698 | jermar | 592 | ipc_answer_0(rid, rc); |
2693 | jermar | 593 | } |
594 | |||
2689 | jermar | 595 | /** |
596 | * @} |
||
597 | */ |